During the 1980s a fable circulated within the US Army concerning Soviet planning for a potential war with the United States. In the most common version, a Soviet general is alleged to have declared in frustration, "It is impossible to plan against the Americans because they don't follow their own doctrine." Many readers of this book will have heard (or said) that "doctrine is only a guide." Indeed, the tactical agility demonstrated by the US Army on the battlefields of Iraq and Afghanistan is due in no small part to a cultural imperative that prizes solutions above all else. While not...